This invention relates to music data transmitting technologies and, more particularly, to a method for transmitting music data information, a music data transmitter, a music data receiver and an information storage medium storing programmed instructions for the music data receiver.
MIDI (Musical Instrument Digital Interface) is a typical example of the music data transmission standards. Data formats are standardized in the MIDI for the music data transmission. According to the MIDI standards, messages are stored in 8-bit data codes, and are transferred between the MIDI interface circuits. Plural 8-bit data codes are required for transferring each message. In other words, each message is represented by using a status byte and data bytes. In the following description, a message defined in the MIDI standards is referred to as xe2x80x9cMIDI messagexe2x80x9d.
FIG. 1 shows the plural 8-bit data codes representative of a MIDI message M. A status byte B1 is followed by data bytes B2 and B3. The status byte B1 is broken down into two parts, i.e., high-order 4 bits (1001) and low-order 4 bits (0001). The high-order 4 bits (1001) represent a binary number corresponding to a hexadecimal number [9], and the low-order 4 bits (0001) represent a binary number corresponding to a hexadecimal number [1]. In the following description, hexadecimal numbers are placed in brackets. The hexadecimal number [9] is representative of xe2x80x9cnote-onxe2x80x9d, and the hexadecimal number [1] is representative of the first channel through which the note-on event is to take place. Thus, the status byte [91] represents an instruction for generating a tone through the first channel.
The data bytes B2 and B3 give details of the instruction. The number of data bytes is predetermined for each of the status bytes. Two data bytes follow the status byte B1 representative of the instruction for generating a tone through the first channel. The first data byte B2 has a bit string (00111100) corresponding to a hexadecimal number [3C], and the hexadecimal number [3C] is indicative of the pitch of the tone to be generated. The second data byte has a bit string (01100100) corresponding to a hexadecimal number [641], and the hexadecimal number [64] is indicative of the loudness of the tone to be generated. Thus, the MIDI message M is representative of the instruction for generating the tone with the pitch [3C] at the loudness [64].
In the following description, a set of status/data bytes representative of a MIDI message is referred to as xe2x80x9cMIDI data wordxe2x80x9d. A MIDI message is stored in a MIDI data word.
While a musician is playing a tune on a musical instrument, the musical instrument generates tones in response to the keys depressed by the musician. The tones are storeable in the MIDI data words as pieces of music data information. This means that the performance is reproducible from the set of MIDI data words. When the MIDI data words are transmitted to another musical instrument, the musical instrument takes out the MIDI messages from the MIDI data words, and reproduces the tones from the MIDI messages. However, the tones are not produced at regular intervals. For this reason, the musical instruments usually communicate with each other through an asynchronous baseband transmission. In the baseband transmission, a transmitting signal is propagated through a transmission path without riding on a carrier wave. The baseband transmission requires a wide frequency range. For this reason, the MIDI data words are hardly transmitted through a communication channel assigned a narrow frequency band. This is the first problem.
The second problem is low transfer efficiency. As described hereinbefore, the MIDI message is stored in the status byte and the data bytes, and a start bit of logic xe2x80x9c0xe2x80x9d level and a stop bit of logic xe2x80x9c1xe2x80x9d level are attached to each byte as shown in FIG. 1B. The status byte and the data byte are prolonged from 8 bits to 10 bits. This results in low transfer efficiency.
It is therefore an important object of the present invention to provide a method for transmitting music data information through which pieces of music data are transmitted at high transfer efficiency.
It is also an important object of the present invention to provide a music data transmitter and a music data receiver both used in the method.
It is yet another important object of the present invention to provide an information storage medium which stores programmed instructions for the music data receiver.
To accomplish the object, the present invention proposes to employ a stuff pulse synchronization technology in the music data transmission.
In accordance with one aspect of the present invention, there is provided a method for transmitting pieces of music data information produced at irregular time intervals from a source of music data to a user comprising the steps of receiving the pieces of music data information supplied from the source of music data, supplementing pieces of synchronous data information among the pieces of music data information for producing a data stream, transmitting the data stream through a propagation path and receiving the data stream, eliminating the pieces of synchronous data information from the data stream so as to leave the pieces of music data information and supplying the pieces of music data information to the user.
In accordance with another aspect of the present invention, there is provided a music data information through a propagation path comprising 1) a first data interface for receiving the pieces of music data information supplied from a source of music data at irregular time intervals, b) a first data converter connected to the first data interface and supplementing pieces of synchronous data information among the pieces of music data information for converting the pieces of music data information to a data stream, and c) a second data interface connected to the first data converter for synchronously transmitting the data stream through the propagation path.
In accordance with yet another aspect of the present invention, there is provided a music data receiver for restoring pieces of music data information on the basis of data stream synchronously transmitted through a propagation path comprising a) a first means for eliminating pieces of synchronous data information from the data stream and b) a second means for extracting the pieces of music data information from the data stream.
In accordance with still another aspect of the present invention, there is provided an information storage medium for storing programmed instructions to be executed for restoring pieces of music data information from a data stream synchronously supplied through a propagation path, and the information storage medium containing a) a first means for eliminating pieces of synchronous data information from the data stream and b) a second means for extracting the pieces of music data information from the data stream.